Fog is frequently required for special effects in the production of films or in theatres.
Fog is also used for the analysis of air flows within, for example, "clean rooms" often used by the manufacturers of medical products.
Fog is currently produced using a variety of methods. For example, it is known to produce fog by passing air over solid carbon dioxide to cool the air and then passing the cooled air over the surface of heated water to entrain water vapor and thus create a fog comprising carbon dioxide, water vapor and air.